Multi-primary LED Collimation Optic Assemblies for Color Uniformity
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Solution Overview
Problem
Conventional multicolor optical light source assemblies struggle to achieve both narrow beam collimation and color uniformity, leading to poor color mixing and illumination uniformity, especially in applications requiring long-distance projection of selected colors with high illuminance.
Innovation Solution
The use of a multi-primary LED collimation optic assembly featuring a spline patch inner lens, TIR lens, lenslet arrays, a ribbed reflector, and secondary collimation lenses, including aspheric and Zernike control surfaces, tailored to match LED placement for enhanced collimation and color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If LEDs are spaced widely apart for improved heat dissipation, then thermal management is improved, but color mixing deteriorates
Solution Approach 1:
A light guide is introduced as an intermediary component between the LED array and the external environment. The light guide collects light from multiple LEDs spaced apart for thermal management and transports it through internal reflective surfaces (total internal reflection) to achieve color mixing before output, thus resolving the contradiction between heat dissipation and color mixing
Solution Approach 2:
The patent transitions from direct spatial overlap of LEDs (2D plane mixing) to 3D light path manipulation within the light guide volume. By using total internal reflection and strategic placement of reflective surfaces, the system achieves color mixing through extended light paths in three dimensions, allowing LEDs to remain spaced apart while still achieving uniform color output
2Speed
If conventional collimation optics are used, then beam direction control is achieved, but color uniformity deteriorates
Solution Approach 1:
The collimation function is segmented into two distinct components: (1) the light guide with its internal reflective surfaces that handles color mixing and initial light direction, and (2) a separate collimation lens that provides final beam collimation. This segmentation allows each component to optimize its specific function without compromising the other, achieving both color uniformity and beam direction control
3Stability of the object's composition
If LED spacing is reduced to improve color mixing, then color uniformity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The light guide acts as a mediator that decouples LED spacing from color mixing quality. By using total internal reflection and extended light paths within the light guide, the system achieves effective color mixing even when LEDs are spaced relatively far apart, thereby reducing the stringency of manufacturing precision requirements for LED placement
4Length of stationary object
If light is collimated to a narrow beam, then projection distance is increased, but color uniformity deteriorates
Solution Approach 1:
The optical system is segmented into a light guide section that optimizes color mixing through internal reflection, followed by a collimation lens section that creates the narrow beam for long-distance projection. This sequential segmentation ensures that color uniformity is established before collimation, allowing the final beam to be narrowly collimated while maintaining the color uniformity achieved in the light guide
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves collimation and color uniformity, enabling high-intensity, uniform light beams that can be projected over long distances with minimal dispersion, optimizing both beam width and color consistency.
Implementation Method 1
TIR lens
Implementation Method 2
spline patch inner lens, at least two lenslet arrays, a rippled reflector, and at least one secondary collimation lens
Data Source
AI summary
The present invention relates to an optical assembly which improves color uniformity and improved collimation of light produced by multiple LED light sources in a light engine. The optical assembly is specifically tailored to match the placement of the solid-state emitters making up the light engine or light producing element. Specifically, a shaped free-form spline patch inner collimation lens having an optimized cross-sectional shape and micro-ridges is used to disperse light; multi-lobe TIR collimation lens having an optimized cross-sectional shape and micro-ridges is used to disperse and redistribute phase as well as provide collimation; primary mixing lenslet array having an optimized surface is used to disperse light from the light emitter; a spline profile reflector further mixes and collimates the light; a secondary lenslet array further mixes the light; and a secondary collimation lens further collimates the light.